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Tuning the ZEQ25, YouTube link

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#1 Astronewb

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Posted 08 October 2013 - 09:49 PM

I finally broke down and made a video on how I tune the ZEQ25. Had to break it into three vids for YouTube, but here's the link to Part 1:

http://youtu.be/-Cjqs4iDW1c

Hopefully you can find the other 2 videos on site?

Clear skies and don't break anything!

Paul

#2 Mkofski

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Posted 08 October 2013 - 10:48 PM

Thanks Paul... I give it a shot tomorrow!

#3 Bill McNeal

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Posted 09 October 2013 - 12:32 AM

Thanks Paul. Will check them out!

#4 Justin neg3deg

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Posted 09 October 2013 - 04:09 AM

Great video, thanks Paul

#5 anat

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Posted 09 October 2013 - 05:18 AM

Paul.

The major problems discussed in this forum are mainly all about the RA play and crosstalk noises. With your video instruction, there is nothing to worry about. Many thanks for your effort.

Anat

#6 Astronewb

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Posted 09 October 2013 - 09:29 AM

Paul.

The major problems discussed in this forum are mainly all about the RA play and crosstalk noises. With your video instruction, there is nothing to worry about. Many thanks for your effort.

Anat


Thanks Anat, hopefully there will be fewer issues now that users can see how to deal with them via a video.

Of course, some careful assembly on the part of iOptron would be ideal. I think the assembly line does not consist of highly skilled workers, unfortunately.

Best,

Paul

#7 ramasule

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Posted 09 October 2013 - 12:42 PM

http://www.youtube.c...h?v=-Cjqs4iDW1c #1

http://www.youtube.c...h?v=JkXnuGQNYS8 #2

http://www.youtube.c...h?v=ejlnH58RR0w #3

#8 Astronewb

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Posted 10 October 2013 - 12:16 AM

Just an update, someone asked me a good question today. He wanted to know how he could tell if he need to tune his mount since it was being delivered new.

I 'thunked' about that and came up with this base test on my mount.

Set your mount up with the counterweight shaft in a horizontal position and the tension screw turned all the way in.

Put the counterweight on, flush with the end of the safety cap.

Tension screw all the way in ... no slippage.

One turn out (360 degrees)..no slippage.

Two turns out...no slippage.

Three turns out...no slippage.

Four turns out...no slippage.

Five turns out..slipped if I just nudged the c/w.

So, the mount, properly adjusted, should hold against the counterweight, with the tension screw backed 4 turns out.

I guess if your mount slips at 1 or 2 turns out...you need to watch the videos and get your tools out?

Clear skies...Paul

#9 rkayakr

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Posted 10 October 2013 - 06:58 AM

Paul

Thanks for the useful diagnostic.

How about a comprehensive iEQ45 tune up video?

Bob

#10 Astronewb

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Posted 10 October 2013 - 08:01 AM

Paul

Thanks for the useful diagnostic.

How about a comprehensive iEQ45 tune up video?

Bob


Thanks Bob, as far as the iEQ45, that would be a 5 or 6 part video upload. Maybe on some snowbound, blustery day, when I absolutely nothing else to do....:)

Best,

Paul

#11 WhistleStop

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Posted 10 October 2013 - 08:49 AM

Paul
You are a "god send" ! I bought my ZEQ25 and immediately found a bad worm in the RA, iOptron was great and sent me a new worm and instructions ( my choice to fix it myself). After the self-repair I found the non guided PE to be max +/- 7.5 arcsec and the guided and corrected to be max +0 / - 0.85.... truly amazing.
To be clear that was done with a light load DSLR, lens, 50mm finder and guide cam. I am really impressed by this mount! And just as impressed by your efforts to educate all of us in tweaking its performance. Thank you, Paul. :bow:
Secretly though, I love the videos as you are a dead ringer for the cult favorite 'Winnebago Man' :roflmao:
Keep up the great work.
Cheers
Lynn
NightoverOntario.com

#12 Astronewb

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Posted 10 October 2013 - 09:49 AM

Thanks so much Lynn.

I guess I'm going to have to Google 'Winnebago Man' to see who's going around pretending to be me?

Glad you enjoy the vids, and I appreciate the nice comments.

Oh, I can confirm the tracking and PE capability of this wonderful little mount too..it's just incredible for a mount in this price range.

All the best,

Paul

#13 Hunlon

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Posted 10 October 2013 - 04:51 PM

Great videos Paul.

A stark contrast to the help that iOptron have been giving me. When I reported that I was measuring PE at 65 arc secs P-P they said it was a little high but there is no designed PE criteria. They also said that the average PE being reported was 30 arc secs P-P. They sent me 2 pdfs to fix the play in the worm drive, which by the way were very confusing, but I found no play in the mechanism. So I just had to settle with what I got - just a variation in the manufacturing.

Your videos, however, indicate that with a little adjustment and replacement of critical parts like the springs I might really have a great mount in my possession. I now know how my mount should behave.

Kudos,
Hunlon.

#14 gramaglia

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Posted 10 October 2013 - 08:44 PM

Thanks for providing another very useful video Paul. I wasn't aware you could access the brass screws without dismounting the worm assembly, I major time savings.

The only thing I would add for those that don't have a modified pulley wheel is on how to reattach the belt on the wheel.
Replace the wheel without tightening the allen screw; make sure the screw is facing up as close as possible to the worm assembly while still being able to be accessed by an allen wrench.
Place the allen wrench on the screw, then attach as much of the belt that will easily get on. At this point pull on the allen wrench allowing the wheel to rotate, this will allow the rest of the belt to catch the wheel.
Once the belt is completely around the wheel even though the outer half will be overhanging tighten the allen screw.
Now easily push the belt on to the wheel so that's it's perpendicular to the motor.

#15 ramasule

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Posted 10 October 2013 - 11:23 PM

That's what I did gram, good point...

I just ripped my whole mount apart (I had no previous problems)
My springs where 1/2 inch but I had the long tension screw. I put a spring inside and slightly longer as Paul has.

Most annoying part, getting the Dec black cover on and off, those screws were annoying.

My side to side adjustments (the part with the small locking screw and the big screw) were to tight. I loosened them up a bit ( we will see how that goes).

Also my Dec backlash was a little sloppy before... The grub screw on the Dec gear was loose, boom fixed.

This is a nice mount to work on, very easy to take apart.

If your having problems squeezing the black cover off, your getting hanged up on the port plugs. Put a small flat in there and gently pry the black case away while pulling up. This is the part Paul suggests to file.

In conclusion thanks Paul for the awesome videos and tricks. I look forward to trying out my tweeks.

Ram

#16 pippo

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Posted 12 October 2013 - 05:25 AM

Dear Paul,
I tuned my mount following your very clear instructions (thanks a lot for your help!). The problem of the RA axis is slightly improved.

Indeed, before the tuning, with counter-weight flushed at the end of the safety cap, the RA axes was slipping even with the screw all the way in. After the tuning the RA axis slips after 1/2 of the turn out.

This could be due to the too weak original springs of my mount (my springs of both axes are uncut and 14mm long).

Could you please repeat on your mount the test with the mount original springs? In this way, we can see if the problem is related to the springs or to the mount....

Thanks

Francesco

#17 ramasule

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Posted 12 October 2013 - 07:31 PM

Pippo,

I have original uncut springs, with uncut screws and I did not experience this slipping. Make sure the ball is seated inside the spring when you reassemble. Take the black cover off and view the RA action as you load it with the counterweight.

#18 Astronewb

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Posted 12 October 2013 - 10:38 PM

Could you please repeat on your mount the test with the mount original springs? In this way, we can see if the problem is related to the springs or to the mount....


Sorry Francesco, took me a while to find the original springs. Installed the original (w/cut coil up)

Counterweight flush with safety cap. Mount in horizontal position.

One half turn..no slippage

One turn..no slippage

One and one half turns..no slippage

Anything more than one and one half...slips.

So the dual spring set contributes quite a bit of holding force on the worm housing.

Ciao,

Paul

#19 pippo

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Posted 13 October 2013 - 03:36 AM

Ok thanks,
so in term of holding force 1.5 turns with the original spring is equivalent to 5 turns with your double springs.
This mean that you can safely use on the mount a much stronger holding force without damaging the motors!
I asked iopteron about changing the springs with stiffer one they answered:
"We don't recommend changing the spring to a strong one; which might risk excess force to the motor if it is not properly adjusted. If customer choose to replace, please
double check the tension adjuster is released EVERY TIME when operate the mount."
What is your experience? If the force is too large, you just get an overcurrent message and the motor stop, or you can burn the motors? How do you judge that the holding force is too large?

PS instead of replacing the spring I just used some refolded aluminum foil to make a 2-3mm thick disk to be inserted in the spring-housing inside the screw before inserting the spring. In term of holding force, the effect of shortening the spring-housing with the disk is equivalent to the use of a stiffer (or longer) spring. However with the disk you avoid to look for new springs and, by varying the thickness of the disk (just adding some extra layers of foil), you can rapidly and finely tune the force.

#20 Astronewb

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Posted 13 October 2013 - 09:43 AM

PS instead of replacing the spring I just used some refolded aluminum foil to make a 2-3mm thick disk to be inserted in the spring-housing inside the screw before inserting the spring. In term of holding force, the effect of shortening the spring-housing with the disk is equivalent to the use of a stiffer (or longer) spring. However with the disk you avoid to look for new springs and, by varying the thickness of the disk (just adding some extra layers of foil), you can rapidly and finely tune the force.


Hello Pippo,

Be very careful with adding material (foil, washers, etc) inside the screw to increase the tension.

The danger is that, if you add too much material, when the screw is turned in, the spring coils may compress all the way and reach 'coil bind' Then you don't have a spring anymore, just a solid piece of metal.

If you run a coil bound spring down against the worm housing, you will get OC messages, and the real possibility of burning out an encoder motor.

Do this, remove your spring, put it in a vise or in a pair of pliers. Measure the distance (length) of the spring, then compress the spring and re-measure the distance. The difference between the two is the maximum free space available. Avoid approaching this figure, make sure whatever spacer you use is less than that figure.

With dual springs, or a heavier spring, even when the tension screw is run all the way down, there is room for the worm housing to move upwards away from the ring, and will not damage the motor. I never even get any OC messages.

Hope that helps,

Paul

#21 pippo

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Posted 13 October 2013 - 03:30 PM

Indeed you are correct. It is too dangerous to add material especially with my 14mm length spring. The remaining space is just 2mm and it is possible to reach the situation you are describing. So I agree with you that is safer to find a stronger spring....

#22 Hunlon

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Posted 14 October 2013 - 05:30 PM

Hi Paul,

It seems to me that if the spacer brings the total length to 1/2" you would have the same spring tension as the original spring. This is because F=kx, where k is the stiffness and x is the compression and it doesn't matter if the spring is 1/4" long or 1/2" long, compressing it by 1/8" will generate the same force. I agree that making the total length longer than 1/2" will risk 'coil bind' so would not be a good idea.

The fact that you get better performance by adding an inner spring indicates that the original spring stiffness is too low and should be increased. The ball is now in iOptron's court. I just hope they've made the appropriate adjustments to their production line.

#23 ramasule

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Posted 14 October 2013 - 06:50 PM

Yes if you compress 1/8" on both springs same force, however a 18mm spring will compress further then a 15mm spring with 3mm spacers.

#24 Hunlon

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Posted 14 October 2013 - 07:40 PM

Yes if you compress 1/8" on both springs same force, however a 18mm spring will compress further then a 15mm spring with 3mm spacers.


Point taken. But the amount of force applied to the worm is proportional to the compression of the spring. This compression is achieved by screwing in the tension knob. The maximum force available is the amount of compression - it doesn't matter how long the spring is. Having a longer spring means that your range of compression is longer and therefore the maximum force is higher but if your screw only compresses the spring by, say, 6mm you will only get 6mm worth.

#25 Tony Finnerty

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Posted 14 October 2013 - 08:31 PM

Thank you, Paul, for the tuning videos. I replaced each tensioning spring with two 0.5 inch springs as suggested, then did the whole tuning thing for both axes. Last night it just worked. PHD gave Osc-index values of 0.16 to 0.27 and RMS 0.10 to 0.15 through approx. 400 subs totalling 5 hours exposure time, with round stars.

Contrast was less in the moon-bright sky, but autoguiding worked well, even though missed guiding steps due to star mass variations (twinkling) were frequent. With short (1 minute using my 100mm, f/2.0 lens) exposures due to sky brightness, I didn't need autoguiding at all. The tuned ZEQ25 is a keeper.






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